Yokogawa Button Operated MV2000 - Manual (Page 156)

7-3 M-4662
Specifications
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App
Index
7.3 Modbus Protocol Specifications
Modbus Client Function
Basic Operation
• The MV, operating as a Modbus client device, communicates with Modbus servers
periodically by sending commands at specified intervals.
• This function is independent of the Modbus master function operating over the serial
interface.
• The supported functions are (1) reading data from the input registers and hold
registers on a server and (2) writing data into the hold registers on a server.
Modbus Client Specifications
Communication available via ModbusTCP
Communication media: Ethernet 10Base-T
Read cycle:
Select from the following:
125 ms, 250 ms, 500 ms, 1 s, 2 s, 5 s, and 10 s
Connection retries: Select the how long to wait before reconnecting after the
connection is dropped due to the expiration of the connection
wait time.
OFF, 10 s, 20 s, 30 s, 1 min, 2 min, 5 min, 10 min, 20 min, 30
min, and 1 h
Connection timeout value: 1 minute
However, if the IP address has not been obtained from the
DHCP server, a communication error results immediately.
Command timeout value: 10 seconds
Server:
Register up to 16 servers
Supported functions: The table below contain functions that the MV supports. To
use the functions, the server device must also support them.
Function Code Function Operation
3 Reads the hold register
(4xxxx, 4xxxxx) The MV reads from the server device hold register
into the communication input channel or external
input channel.
4 Reads the input register
(3xxxx, 3xxxxx) The MV reads from the server device input register
into the communication input channel or external
input channel.
16 Writes to the hold register
(4xxxx, 4xxxxx) The MV writes the measured or computed data to
the server device hold register.
Commands
Command type: R, R-M, W, and W-M
Number of commands: Set up to 16 commands
Data type:
See the table below.
Symbol Description
INT16 16-bit signed integer
UINT16 16-bit unsigned integer
INT32_B 32-bit signed integer (big endian)
INT32_L 32-bit signed integer (little endian)
UINT32_B 32-bit unsigned integer (big endian)
UINT32_L 32-bit unsigned integer (little endian)
FLOAT_B 32-bit floating point (big endian)
FLOAT_L 32-bit floating point (little endian)